Building construction sites for large buildings frequently employ aerial lift equipment for lifting operatives to elevated locations for, for example, the installation of overhead pipework during the construction of a building.
A typical aerial lift may comprise a mobile self drive lift having an extendable boom which has an elevator basket or cage for housing operatives secured to the end of the boom. The basket may contain a control panel which permits a user standing the basket or cage to manoeuvre the cage to a raised location which facilitates the carrying out of work. The boom is typically raised by a powered hydraulic system on the vehicle.
The controls in elevator baskets typically include foot operable safety switch which needs to be closed before controls on the operator panel may be operated. If the safety device is released the movement of the basket ceases immediately. However, it has been known for some operators to cut out safety procedures by jamming the switch into a closed position by the use of a foreign body such a piece of wood. In such a situation if the operator standing at the controls is disabled by accident when the basket is in a raised condition, if the operator is caused to releases release the movement control lever, the movement of the basket ceases gradually. If the operator had become accidentally trapped between the basket and some other object, this extra movement may give rise to serious injury or may even be fatal to the operator. In some circumstance, operators have not always been hit the emergency stop provided on the control panel. A similar situation may arise when the operator is disabled but their foot remains trapped on the safety switch.
In the event that the operator is being asphyxiated and is working on their own, their predicament may not be known to others in the vicinity, then the operator may not be freed within the critical time period which is up to four minutes of the operator being unable to breathe.
The present invention provide a safety device which will help prevent death or serious injury in the event of the foot safety switch remaining closed when an operator is disabled and will warn others in the vicinity that a serious incident has occurred.